The keyboard-video-mouse (KVM) switch interconnecting a plurality of console devices and a plurality of computers with conditioning circuits coupled to the corresponding console devices and computers is a so-called matrix KVM switch. It is a solution to the access of computers through the matrix cross switch to remotely control the selected computers at the console device for multi-users. Referring to FIG. 1, a traditional matrix cross switch for interconnecting a plurality of remote console devices and computers is shown. The prior arts related with such traditional cross switch has been disclosed in U.S. Pat. No. 5,721,842, U.S. Pat. No. 5,884,096, U.S. Pat. No. 5,937,176, U.S. Pat. No. 6,345,323 and U.S. Pat. No. 6,112,264. The cross switch 114 manages all the keyboard-video-mouse signals for routing the remote console devices (102, 104 or 106) to one of the selected computers (108, 110 or 112). Furthermore, the cross switch cannot work as far as what it's required practically without the cooperation of the conditioning circuits (120, 122, 124, 126, 128, 130). The principle of the cross switch is described below.
First, the user selects one computer at one remote console device. From the remote console device, the user sends the keyboard, mouse signals through the conditioning circuit coupled to the remote console device, the cross switch 114 and then the conditioning circuit coupled to the selected computer to control the selected computer, and receive the video signals for showing on the monitor of the remote console device in reverse order. For example, if the user selects the computer 108 at the remote console device 102, the other computers 110 or 112 will not receive the keyboard or mouse signal from the remote console device 102. At the remote console side, the user operates the keyboard and mouse to send the keyboard, mouse signals from the extender 120, via the cross switch 114 and the conditioning circuit 126 to control the computer 108. For showing the operating status on the monitor of the remote console device for the user simultaneously, the video signals from the computer consequent on the operating of the keyboard and mouse was sent from the conditioning circuit 126, through the cross switch 114 and the conditioning circuit 120 back to the remote console device to be shown on the monitor for user. The other user can operate at the other remote console devices as the same even at the same time. Consequentially, no matter at any of the remote console devices (102, 104, 106) the user can control any of the computers (108, 110, 112) with the cross switch working with the conditioning circuits for practical requirement. Further, the purpose of the multi-console devices is to allow multi-user operation to different computers at the same time.
However, the cross switch 114 is complicated and costly. On the other hand, once the cross switch 114 crashed, the communication of whole architecture 100 becomes dead due to its center position in mainly managing all the keyboard-video-mouse signals among the remote console devices and computers. Each of the users who are operating at the remote console devices takes a risk equally. Moreover, the reason for using the conditioning circuits is only to extend the distance, between the specific remote console device and the cross switch 114, also between the cross switch 114 and the specific computer. Unfortunately, the existing conditioning circuit still has limitation in extending the distance between the remote console device and the computer. Generally, the extended distance of the current conditioning circuit that allows the user to remotely control the computers or KVM switch is up to 150 meters. Some might reach up to 300 meters. Practically, the manufacturers still keep working on better design to extend the distance that the conditioning circuit allows for users definitely demand. However, it has to take lots of efforts to prevent the transmission decay of the keyboard-video-mouse signals when the desired distance is longer as one cable is used. Consequentially, there's a need of a matrix architecture for conditioning circuit to avoid a crash of the whole architecture 100 as using only one cross switch 114 for transmitting signals. Also, there is a demand for distance extension between the console terminals and computers.